diff --git a/pyproject.toml b/pyproject.toml
index 7f1c8d8..02ca01c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -45,7 +45,7 @@ dependencies = [
     "ruff==0.15.12",
     "aiohttp==3.13.5",
     "prometheus-client==0.25.0",
-    "mashumaro==3.20",
+    "mashumaro==3.21",
     "mkdocs-material==9.7.6",
     "mkdocstrings[python]==1.0.4",
     "pytest-asyncio==1.3.0",